Sag resistant, high performance, two component epoxy structural adhesives

ABSTRACT

An adhesive composition which results from the mixture of two components, the first component comprising a polyepoxide and the second component comprising a finely dispersed solid salt of a polyamine and a polyphenol in a liquid adduct of a poly(alkylene oxide) polyamine and a polyphenol and the use of this non sagging, high performance adhesive in structural applications is described.

This invention relates to two component epoxy adhesive compositionswhich are sag resistant, have long ambient temperature open time andcure rapidly at moderately elevated temperatures with excellent adhesionperformance towards structural substrates comprising as first componenta rubber modified epoxy resin having low dilatency and a secondcomponent comprising a mixture of a finely dispersed solid salt of apolyamine with a polyphenol in a liquid adduct of a long chainpoly(alkylene oxide) di- or triamine with polyphenols and to a processfor the manufacture of said compositions.

The two component epoxy adhesives of this invention when mixed have longambient temperature open time (pot life) and cure readily at moderatelyelevated temperatures after mixing with excellent adhesion performancetowards primed or non-primed structrual substrates such as fiberreinforced plastics including sheet molding compounds (SMC), metals,glass, other ceramics, and the like. Each of the two components of theadhesives of this invention is a stable thixotropic material having lowdilatency.

Most of the prior art two component epoxy adhesives are cured bycommonly available low molecular weight amine curing agents and areknown to have relatively short pot life and the cured adhesives whichresult from them are usually very stiff, brittle and have low elongationand flexibility, thus showing low energy absorbing properties whichmight cause problems such as bond deformations (readout) in the adheredsubstrates such as fiberglass reinforced plastics. Prior art use offlexibilizers, such as polyurethane elastomers or rubbers in twocomponent epoxy adhesives in quantities sufficient to be beneficial,often results in significant increase in the viscosities of thecomponents and loss of some physical performance in the cured adhesiveas well as the loss of cure speed for the adhesive. Use of certaincombinations of poly(alkylene oxide) polyamines has been described inU.S. Pat. Nos. 3,306,809; 3,645,969 and 4,485,229 to give flexible epoxypolymers. Most of these systems lack several important processing andadhesive performance properties including sag resistance of the mixedadhesive (non flowability of the mixed adhesive when applied to verticaland other non horizontal surfaces of substrates) and long roomtemperature open time (pot life or use time) and at the same time havingthe ability to cure rapidly under moderately elevated temperatures. Theuse of polyamine salts of polyphenolics dispersed in liquidpoly(alkylene oxide) polyamine adducts with polyphenolics as hardener inthe two component, sag resistant, high performance structural adhesivehaving several hours to days of ambient terperature open time (pot life)and rapid curing (few minutes) at moderatley elevated temperatures (80°C. to 150° C. and preferably 80° C. to 120° C.)has not heretofore beendisclosed in the art for the bonding of structural substrates such asfiberglass reinforced plastics, metals, glass, and the like.

Two component mixtures of epoxy resins and conventional amine curingagents used as adhesives generally have a short ambient temperature potlife, i.e., remain free flowing and uncured for only a short time afterthe two components are mixed to form the active adhesive and theadhesive compositions based on these polymeric compositions usuallyexhibit reasonably good adhesion properties toward stiff and highmodulus structural substrates such as metals and reinforced compositematerials. Such materials usually give rigid, stiff and brittle curedadhesive bonds and generally fail to provide good adhesion bonding withstructural substrates having low-to-medium modulus (for instancefiberglass reinforced plastic, FRP and fiber reinforced plastic or SMC).Furthermore, because of the poor flexibility and low elongationproperties of these prior art adhesives, they also can cause stressdeformation in the bond line between the cured adhesive and thestructural substrate particularly when the substrate is a plasticmaterial.

Considerable efforts have been devoted by those skilled in the art todeveloping flexible epoxy polymer compositions by using additives suchas plasticizers, thermoplastics and monoepoxide diluents; however, theseusually have resulted in loss of adhesion performance at elevatedtemperatures as well as having caused processing problems such asincreased viscosities and relatively longer curing times. Certain epoxycompositions described in U.S. Pat. Nos. 3,306,809; 3,645,969 and4,485,229 using long chain poly(alkylene oxide) polyamines as curingagents have been described as being flexible and as providing goodadhesion toward metal substrates. Such compositions lack one or more ofthe desired features of the high performance adhesives useful inautomated bonding applications such as bonding of fiberglass reinforcedplastic parts to themselves or to other substrates such as metal, glassor ceramic in automotive assembly requiring non sagging properties withlong open time at ambient temperatures, fast curing at moderatelyelevated temperature, and other desirable properties for this type ofapplication.

Some of the more desirable features of two component structuraladhesives include:

Individual components of low dilatency and easy pumpability.

Non sagging character of the mixed adhesive bead thickness up to 1/2inch immediately after mixing of the two components.

Non critical mix ratios (ratio tolerance in mixing of the twocomponents).

Long ambient temperature (application temperature) open time (pot life),requiring no cleaning or flushing of the mixer for several hours todays. This is to minimize the waste and disposal costs.

Rapid green strength (handling strength of about 50 psi) buildup uponheating at moderately elevated temperatures (below about 120 degreesC.).

No need of rigorous surface preparation (cleaning, scratching,scrubbing, priming, and the like).

High flexibility and tough adhesive bond with high shear and peelstrength.

Low hygroscopicity of adhesive.

High heat resistance (ability to remain stable even at 400 degrees F.for one hour).

The present invention provides compositions of two component structuraladhesives having sag resistance, ambient temperature open time ofseveral hours to several days and cure rate at moderately elevatedtemperatures (below 120 degrees C.) of a few minutes. These compositionsprovide excellent adhesion toward unprimed substrates and possess all ofthe above-described desirable properties. The adhesive compositions ofthis invention comprise mixtures of two stable components, namely, (A)an epoxy resin component comprising a polyepoxide which optionally canbe modified by reacting partially with a carboxylic acid terminatedrubber up to 20% by weight of rubber per weight of the epoxy resin) andoptionally blended with a polyurethane elastomer, phenol or oximeblocked isocyanate prepolymer and di- or triglycidyl ether of a poly(alkylene glycol) (up to 15% by weight of the total epoxy resin) and (B)the hardener component or curing agent component which comprises afinely dispersed solid salt (or adduct) of a mono-, di- or polyaminewith polyphenol in a liquid adduct of poly(alkylene oxide) polyamine(molecular weight ranging from 200 to 10,000) with a polyphenol inweight ratio of solid salt to liquid adduct of polyphenol-poly(alkyleneoxide) polyamine ranging from 5:95 to 60:40 and preferably 10:90 to50:50 respectively.

Polyepoxides useful in this invention can be monomeric or polymeric,saturated or unsaturated, aliphatic, cycloaliphatic, aromatic orheterocyclic, and they may be substituted if desired with othersubstituents besides the epoxy groups, e.g., hydroxyl groups, etherradicals, halogen atoms, and the like.

Typical polyepoxides suitable in the practice of this invention includethose disclosed in U.S. Pat. Nos. 2,500,600 and 2,324,483 which areincorporated herein by reference. Preferred in this invention are1,2-epoxy compounds having an epoxide equivalence greater than 1, thatis to say, compounds containing more than one group of the formula:##STR1##

The 1,2-epoxide groups may be either terminal or inner ones.Particularly suitable terminal 1,2-epoxide groups are 1,2-epoxy ethyl or1,2-epoxy propyl groups. The latter may be linked to an oxygen atom,that is to say, they are glycidyl ether or glycidyl ester groups.Compounds with inner epoxide groups usually contain the 1,2-epoxidegroup in an aliphatic chain or in a cycloaliphatic ring.

As polyepoxides containing an inner 1,2-epoxy group there are suitableepoxidized diolefins, dienes, or cyclic dienes, such as 1,2,5,6-diepoxyhexane, 1,2,4,5-diepoxy cyclohexane, dicyclopentadiene diepoxide,dipentene diepoxide, vinyl cyclohexene diepoxide, epoxidizeddiolefinically unsaturated carboxylic acid esters such asmethyl-9,10,12,13-diepoxy stearate or the dimethyl ester of6,7,10,11-diepoxyhexadecane-1,16-dicarboxylic acid. Furthermore, theremay be mentioned epoxidized mono-, di-, or polyesters and mono-, di-, orpolyacetals containing at least one cycloaliphatic 5-membered or6-membered ring, to which at least two 1,2-epoxidized groups are linked.

A widely used class of polyepoxides which can be used in the presentinvention are the epoxy polyethers obtained by reacting a halogencontaining epoxide or dihalohydrin, such as epichlorohydrin,epibromohydrin, 3-chloro-1,2-epoxyoctane, and the like with either apolyhydric phenol or a polyhydric alcohol.

The epoxy resin component of this invention may contain from about 2 to40% by weight of a filler or fillers such as talc, kaolin, aluminumoxide, metal oxides, ferromagnetic fillers, and the like and thethixotropic character can be built up by addition of fumed silica(hydrophobic or hydrophilic) in amounts of from about 1 to 8% by weight.Optionally, additives having hydrogen bondable protons, for instance,glycerine to activate the fumed silica is also within the scope of thisinvention. Optionally, additional chemical thixotropic materials such asthose described in U.S. Pat. No. 4,578,424 may also be included in thiscomponent.

In the hardener component the solid salts or adducts are formed fromamines including monoalkyl and dialkyl monoamines such as ethyl amine,propylamine, butylamine, cyclohexyl amine, diethylamine, dipropylamine,dicyclohexylamine and the like, alkenyl di- and polyamines such asethylenediamine, propylene diamine butylene diamine, cyclohexanediamine, bisamino-methyl cyclohexane isophorone diamine,diethylenetriamine, triethylenetetramine, dipropylene triamine,piperazine and the like, mixed primary secondary and tertiary aminogroup containing amines such as aminoethylpiperazine,bis(aminopropyl)piperazine and the like.

The polyamines useful in forming the solid salt additive curativecomponent of this invention include diamines and may contain anycombination of primary, secondary, and tertiary aliphatic or aromaticamine groups. Preferred polyamines are those which when used separatelyas curatives for epoxy resins are highly reactive, providing rapid curesat room temperature and form solid adducts with polyphenols. The adductsin the curative component of this invention permit the use of suchhighly reactive amines as 1,3-propanediamine, ethylenediamine,1,6-hexamethylenediamine, N,N-dimethyl-1,3-propanediamine,N,N-diethyl-1,3-propanediamine, diethylenetriamine, triethylenetetramineand imino bis(propylamine). Many other polyamines of the foregoing typeswhich may be used will be apparent to those skilled in the art.

The polyphenols useful in formation of the solid adduct used in thehardener component of this invention include Bisphenol-A, resorcinol,4,4'-dihydroxy biphenyl, 1,5-dihydroxy naphthalene,2,4,4-trimethyl-2',4',7-trihydroxy flavan, phenol formaldehyde resins(resole and novolac type polyphenols) and others. Thepolyamine/polyphenol adducts described in U.S. Pat. Nos. 2,076,707 and3,520,905 which are i incorporated herein by reference are useful inthis invention. U.S. Pat. No. 3,520,905 also describes the use of solidpolyamine/polyphenol (flavan salt) as a latent curing agent for singlecomponent epoxy compositions. The salts which cure epoxy resins at areasonably fast rate do not show good shelf life and the salts whichprovide long shelf life, in fact, require a long time to cure the epoxyresin at elevated temperature and are not suitable for rapid adhesivebonding application described herein. In other words, the prior artdescribes one component adhesive systems having long shelf life which donot cure rapidly and the faster curing systems are not stable at ambienttemperatures for more than a few days. Furthermore, the prior artadhesives are stiff and show poor adhesive performance in SMC bonding.The adhesive compositions of this invention are made up of two verystable components having shelf lives of months and they have sagresistance and strong, flexible bonding.

The liquid adducts of long chain poly(alkylene oxide) polyamines andpolyphenols essential to the hardener component of this invention arecomposed of long chain poly(alkylene oxide) polyamines such as thoseprepared by amination of poly(alkylene oxide) polyols as poly(propyleneoxide) di- and tri-amines of molecular weight ranging from 200 to10,000, and the polyphenols include those disclosed above.

One of the methods for preparing the hardener component of the presentinvention is to disperse the preformed, finely powdered solid adduct ofthe polyamine-polyphenol in the liquid adduct of poly(alkylene oxide)di- or triamine (molecular weight ranging from 200 to 10,000)-polyphenolusing known dispersing methods including shearing, milling, etc. and themixture may optionally be filled with fillers such as talc, kaolin,aluminum oxide, powdered metals and metals oxides, etc. and thixotropicfillers such as fumed silica, clays, etc.

A more preferred method for formation of the hardener component is todevelop the solid polyamine/polyphenol adduct particles in uniformlydispersed form, in situ, by reacting (adding) the short chain mono-, di-or polyamine in the solution of polyphenol in poly(alkyleneoxide)polyamine under continuous shear mixing. The amount of polyphenoldissolved in the poly(alkylene oxide) polyamine is the combinedstoichiometric amount of polyphenol needed for the adduct with both thepoly(alkylene oxide) polyamine and short chain mono-, di- or polyamine.The advantage of using this method is manifold: (1) it provides auniform dispersion of finely divided particles of solidpolyamine/polyphenol rapidly, (2) it provides an excellent thixotropicpaste, thus requiring no need of additional thixotropic materials suchas fumed silica and clays which generally are expensive and require goodshearing in order go be activated and (3) the process requires noexpensive milling equipment which also takes a very long time to giveproper dispersion. In this process for preparing the hardener, fillers(up to 40% by weight of the total hardener) may be added either prior tothe salt formation or after the salt formation. Optionally, other curingagents and accelerators known in the art may be added to the hardenercomposition.

The adhesive compositions obtained by mixing the two components of thisinvention generally provide excellent non sag material and beads ofthicknesses up to 0.5 inch may be made without any or little saggingwhen applied to vertical surfaces. The mixed adhesive materials of thisinvention show ambient temperature open time ranging from several hoursto several days, thus avoiding any need for cleaning of the mixing orapplication equipment immediately after use. The adhesives of thisinvention cure rapidly at temperatures in the range of from about 80° to150° C. and preferably from 100° to 120° C. to give tough, flexiblepolymers which exhibit excellent adhesive performance under variousenvironmental conditions on structural substrates such as SMC, coldrolled steel, aluminum, ceramics, glass and the like without the need ofany preliminary surface preparation of the substrate and can be employedusing wide variation in the mix ratios of the epoxide resin component tohardener component.

This invention is further illustrated in the following representativeexamples.

EXAMPLE 1

This example describes a general procedure for the preparation ofadducts (salts) of Bisphenol-A and various polyamines. To the stirredsolution of Bisphenol-A in a solvent such as ether or toluene was addeddropwise a solution of the polyamine in the same solvent in the propermolar ratio of Bisphenol-A to polyamine. The insoluble solid whichformed was separated either by filtration or decantation, was washedwith the solvent followed by drying under reduced pressure. In a typicalcase, 45.6 g of Bisphenol-A was dissolved in 350 ml of diethyl ether. Tothis solution, under mechanical stirring, was added 12 g of ethylenediamine in 250 ml of diethyl ether. An immediate crystalline solidformed which was isolated by filtration, washed with two separate 50 mlportions of diethyl ether and was then dried under reduced pressure togive a free flowing white powdered solid adduct of Bisphenol-A andethylene diamine. Other salts described in the following examples whichwere composed of various other amines and Bisphenol-A were prepared in asimilar manner to that just described.

EXAMPLE 2

This example demonstrates that the curing of diepoxide resin with thesolid salt of a low molecular weight polyamine and a polyphenolic (e.g.,Bisphenol-A) results in a hard, brittle polymer and is for comparativepurposes and is outside the scope of this invention. To 10 g of liquiddiglycidyl ether of Bisphenol-A modified with 10% by weight of acarboxylic acid group terminated butadiene/acrylonitrile (18% by weightof acrylonitrile in the rubber) Hycar rubber (from BF Goodrich), wasdispersed 2.4 g of powdered adduct of Example 1. A 6 g portion of thismixtue was kept at room ethylene diamine/Bisphenol-A prepared by theprocedure of temperature and it became partially gelled in about 10hours. The remaining portion was cured at about 230 degrees F. andgelation occurred within one minute and 40 seconds to give a solidpolymer. This polymer was postcured at 280 degrees F. for 30 minutes andthe resulting polymer was found to have a Shore hardness "D scale" of 80and was very stiff (shore D hardness above 70 is too brittle). Anyattempt to test this polymer specimen for flexibility resulted in abrittle, shiny break with no showing of any flexibility.

EXAMPLE 3

The liquid adduct of poly(propylene oxide) triamine (molecular weight ofabout 3100) with Bisphenol-A was prepared by heating the two componentsin a 7:1 weight ratio, respectively, at 80 degrees C. for about onehour. In a 6 g portion of the resulting liquid adduct was dispersed 2.4g of the powdered ethylene diamine/Bisphenol-A adduct described inExample 2. The resulting hardener component was mixed with 10 g ofliquid diglycidyl ether of Bisphenol-A modified with 10% by weight ofthe rubber described in Example 2. A 10 g portion of this mixedcomposition was kept at room temperature for open time determination andit showed partial gellation in about 10 hours at ambient temperature.The remaining portion of the mixture was cured at 230 degrees F. andgelation occurred in about two minutes to give an infusible solidpolymer. This polymer was postcured at 280 degrees F. for 30 minutes andthe resulting polymer was found to have a Shore hardness D of 45 and wasquite flexible. A 1/8 inch thick sheet of the cured polymer could bebent readily without breaking.

EXAMPLE 4

The procedure of Example 3 was followed using 4.9 g of the hardenercomposition containing 4 g of the liquid adduct of 7:1 (by weight) ofpoly(propylene oxide) triamine with Bisphenol-A and finely dispersed 0.9g of powdered ethylene diamine/Bisphenol-A and mixing it with 5 g of theliquid diepoxy resin described in Example 2. The resulting mixture wasfound to have a room temperature open time of about 12 hours and whenheated at 220 degrees F. was found to cure within three minutes to givean infusible polymer. The polymer after postcuring at 280 degrees F. for30 minutes was found to have a Shore hardness D of 35.

EXAMPLE 5

A 1.5 g sample of the powdered 1:1 molar adduct of aminoethyl piperazinewith Bisphenol-A was dispersed in 1.5 g of the liquid adduct ofpoly(propylene oxide) diamine (molecular weight of about 2000) withBisphenol-A in an 8:1 weight ratio. The resulting hardener compositionwas mixed with 5 g of the diepoxy resin described in Example 2 and themixture was heated at 230 degrees F. Gelation of the heated mixtureoccurred within two minutes to give a white solid polymer which, afterpostcuring at 280 degrees F. for 30 minutes was found to have a Shore Dhardness of 55. In comparison, when the epoxy resin was cured with thesolid aminoethyl piperazine/Bisphenol-A adduct alone in a one-componentsystem, the resulting polymer (which is outside the scope of the presentinvention) had a Shore D hardness of 78 and was brittle.

EXAMPLE 6

This example describes another procedure for the preparation of thehardener component useful in the two component structural adhesives ofthis invention. The mixture of liquid adducts of long chainpoly(propylene oxide) polyamine with Bisphenol-A was prepared bydissolving 9 parts by weight of Bisphenol-A in 60 parts by weight ofpoly(propylene oxide) triamine (molecular weight 400). To this viscousliquid at room temperature was added 25.4 parts by weight of thepowdered 1:1 (molar) adduct of ethylene diamine with Bisphenol-A havinga particle size smaller than 100 mesh and the resulting mixture wasmixed with shearing for about two hours using a mechanical stirreroperating at a speed of about 1400 rpm. The resulting pasty material wasfilled with 30 parts by weight of dry talc filler. The resulting pastyhardener was mixed with 1% by weight of hydrophilic fumed silica whichprovided the thixotropy. This hardener was used in the cure of the epoxyresins as described in the following Examples.

EXAMPLE 7

The epoxy component was prepared by reaction of 63.3 parts by weight ofliquid diglycidyl ether of Bisphenol-A (epoxy equivalent weight of about190) with seven parts by weight of a carboxylic acid terminatedbutadiene/acrylonitrile rubber (18% by weight of acrylonitrile in therubber) and blending this with five parts by weight of diglycidyl etherof poly(propylene oxide) diol (epoxy equivalent weight of about 320),18.7 parts by weight of talc and 6 parts by weight of fumed silica. Theresulting mixture was degassed to give a highly viscous pasty material.

EXAMPLE 8

The hardener component having the same chemical materials as thatdescribed in Example 6 except that the solid adduct of ethylene diaminewith Bisphenol-A was formed in situ, was prepared by using the followingmethod. A solution of 60 parts by weight of poly(propylene oxide)triamine (molecular weight of about 3100), 5.3 parts by weight ofpoly(propylene oxide) diamine (molecular weight of about 400) and 29.6parts by weight of Bisphenol-A was prepared by heating the mixture at 80degrees C. for one hour under constant stirring. To this liquid wasadded 5.3 parts by weight of ethylene diamine under constant high shearat near room temperature. An immediate white thixotropic paste formed.This paste was filled with 30 parts by weight of dry talc and themixture was sheared for 15 minutes followed by degassing under reducedpressure to give the thixotropic paste hardener component.

EXAMPLE 9

The following general procedure for the preparation of adhesive bondswas used throughout the Examples herein.

The two components, i.e., the epoxy component and the hardenercomponent, were mixed in appropriate weight amounts at room temperature.The mixed thixotropic adhesive was applied in the form of 3/8 inch beadsacross the surface of the substrate (usually SMC laminates) which was inthe form of a sheet measuring 12 inches by 4 inches by 100 mils(thickness) was dry wiped before the application. After sprinkling a few30 mils diameter glass beads on top of the adhesive to get a final glueline thickness of 30 mils, a second sheet was then placed on top of thefirst with adhesive in between and leaving a one inch overlap of thesheets. The resulting structures were then cured in a heated fixture at230 degrees F. under a pressure of one psi for 3-4 minutes. Testspecimens were cut from the cured samples in the form of one inchstrips. In this manner several lap shear and side impact test sampleswere prepared for each adhesive tested.

The following test procedures were carried out using at least threesamples for each type of test:

A. Shear strength test at room temperature.

B. Postbaking at 400 degrees F. for an additional one hour and shearstrength test at room temperature.

C. Lap shear strength test at 130° F. after immersion for 7 days in 130°F. water.

Several commercially available sheet molding compound (SMC) laminateswere tested and the results obtained were found to be similar in eachcase.

EXAMPLE 10

The hardener composition of Example 6, having no fumed silica (10 g),was mixed with the epoxy component of Example 7 (10 g) for approximatelyone minute. The resulting paste was found to have some sag when appliedto a vertical surface. In order to obtain the thixotropic adhesive bead,10 g of the hardener component of Example 6 having 1% by weight of fumedsilica was mixed with 10 g of the epoxy component of Example 7. Thethixotropic material which resulted was found to have room temperatureopen time of greater than six hours and 230 degree F. cure time of abouttwo minutes. This adhesive was applied to sheet molding compound sheetsto form adhesive bonds by the procedure given in Example 9 and lap shearstrength testing was carried out. The results of thes test are given inTable 1.

                  TABLE 1                                                         ______________________________________                                        Sample No. Test Procedure                                                                            Lap Shear Strength (psi)                               ______________________________________                                        1          A           370 DL                                                 2          A           325 DL                                                 3          A           310 DL                                                 4          B           245 DL                                                 5          B           260 DL                                                 6          B           315 DL                                                 7          C           215 DL                                                 8          C           240 DL                                                 9          C           300 DL                                                 ______________________________________                                         DL = Substrate Delaminated                                               

EXAMPLE 11

The hardener component of Example 8 (10 g) and the epoxy component ofExample 7 (10 g) were mixed to give a non sagging thixotropic structuraladhesive. Adhesive bonds were prepared by the procedure of Example 9 andthe test results are given in Table 2.

                  TABLE 2                                                         ______________________________________                                        Sample No. Test Procedure                                                                            Lap Shear Strength (psi)                               ______________________________________                                        1          A           340 DL                                                 2          A           380 DL                                                 3          A           340 DL                                                 4          B           240 DL                                                 5          B           270 DL                                                 6          B           300 DL                                                 7          C           225 DL                                                 8          C           240 DL                                                 9          C           310 DL                                                 ______________________________________                                    

EXAMPLE 12

An epoxy component was prepared by following the procedure of Example 7using 63 parts by weight of liquid diglycidyl ether of Bisphenol-A, 7parts by weight of a carboxylic acid terminated butadiene/acrylonitrileHycar rubber, 5 parts by weight of phenol-blocked toluene di-isocyanateprepolymer (blocked NCO of 2.4% by weight), 15 parts by weight of talc,6 parts by weight of fumed silica and 0.5 parts by weight of glycerine.This thixotropic material was degassed under reduced pressure.

EXAMPLE 13

A hardener component was prepared by following the procedure of Example8 using 200 g of poly(propylene oxide) diamine (molecular weight ofabout 4000), 92 g of Bisphenol-A, 80 g of talc and 24 g ofethylenediamine. The resulting thixotropic paste was degassed underreduced pressure.

EXAMPLE 14

The epoxy component of Example 12 (12 g) and hardener component ofExample 13 (10 g) were mixed to give a thixotropic paste havingexcellent non-sag character. This adhesive had open time of about sixhours and a 230 degree F. cure rate of two minutes and 10 seconds. Theadhesive bonds prepared by following the procedure of Example 9 showedsubstrate delamination with lap shear strengths of 200 to 400 psi whentested using testing procedures A and B.

EXAMPLE 15

A polyamine/Bisphenol-A adduct was prepared by reacting bis(aminopropyl)piperazine with Bisphenol-A in 1:2 molar ratio in diethyl ether and theadduct was recovered as a white crystal in solid with melting point of158-160 degrees C. When this salt was mixed with the epoxy resin ofExample 2 in the weight ratio of 1:4 salt to resin, the mixture showedroom temperature pot life of about two weeks and 230 degrees F. curerate of two minutes and forty seconds to give a hard polymer which had aShore D hardness of 80 after postcuring at 280 degrees F. for 30minutes.

EXAMPLE 16

A hardener component was prepared by following the procedure of Example6 using 58 g of poly(propylene oxide) triamine (molecular weight 3100),7 g of poly(propylene oxide) diamine (molecular weight of 400), 10.5 gof Bisphenol-A and 25 g of the bis(aminopropyl) piperazine/Bisphenol-Aadduct of Example 15. The pasty material was filled with 43 g of talc.The resulting hardener component, when mixed with the epoxy resincomponent of Example 7 (1:1 by weight ratio), had poor non-sagproperties indicating the need for a thixotropic additive such as fumedsilica or preparation of solid adduct in situ as in example 8. Theadhesion testing was carried out by following the procedure of example 9and the results are given in Table 3.

                  TABLE 3                                                         ______________________________________                                        Sample No. Test Procedure                                                                            Lap Shear Strength (psi)                               ______________________________________                                        1          A           360 DL                                                 2          A           370 DL                                                 3          A           370 DL                                                 4          B           290 DL                                                 5          B           300 DL                                                 6          B           320 DL                                                 7          C           200 DL                                                 8          C           340 DL                                                 9          C           325 DL                                                 ______________________________________                                    

EXAMPLE 17

A hardener component was prepared by following the procedure of Example8 using 60 parts by weight of poly(propylene oxide) triamine (molecularweight 3100), 5.3 parts by weight of poly(propylene oxide) diamine(molecular weight 400), 30 parts by weight of Bisphenol-A, 5 parts byweight of bis(aminopropyl) piperazine and 30 parts by weight of talc.The resulting thixotropic pasty hardener (10 g) was mixed with the epoxycomponent of Example 12 to give a non thixotropic adhesive which hadroom temperature open time of several days (greater than 3 days) and 230degree F. cure speed of about 3 minutes and 30 seconds. Test results fortests carried out using this adhesive in accordance with the procedureof Example 9 are given in Table 4.

                  TABLE 4                                                         ______________________________________                                        Sample No. Test Procedure                                                                            Lap Shear Strength (psi)                               ______________________________________                                        1          A           440 DL                                                 2          A           380 DL                                                 3          A           320 DL                                                 4          B           300 DL                                                 5          B           255 DL                                                 6          B           345 DL                                                 7          C           250 DL                                                 8          C           300 DL                                                 9          C           315 DL                                                 ______________________________________                                    

EXAMPLE 18

The procedure of Example 8 was followed using a solution of 48.6 g ofBisphenol-A in 80 g of poly(propylene oxide) triamine (molecular weight3100) and 10 g of poly(propylene oxide) diamine (molecular weight ofabout 400) and filling the resulting mixture with 40 g of dry talcfollowed by dropwise addition of 4.6 g triethylenetetramine under highspeed shear. A white thixotropic pasty material formed. This hardenercomponent was mixed with the epoxy component of Example 12 in 1:1 weightratio to give a thixotropic adhesive composition having excellentnon-sag character. The resulting adhesive was found to have a roomtemperature open time of more than one day and a 230 degrees F. curerate of three minutes and thirty seconds. Adhesive bonds were preparedfollowing the procedure of Example 9 using unprimed fiberglassreinforced polyester substrates (SMC), and lap shear strengths weretested as in Example 9. The results of these tests are given in Table 5.

                  TABLE 1                                                         ______________________________________                                        Sample No. Test Procedure                                                                            Lap Shear Strength (psi)                               ______________________________________                                        1          A           430 DL                                                 2          A           450 DL                                                 3          A           405 DL                                                 4          B           350 DL                                                 5          B           360 DL                                                 6          B           380 DL                                                 ______________________________________                                    

I claim:
 1. A two component epoxy resin adhesive composition comprisinga first polyepoxide component and a second curing component consistingessentially of a finely dispersed solid salt of a polyamine and apolyphenol, said polyamine being at least one member selected from thegroup consisting of 1,3-propanediamine, ethylene diamine,1,6-hexamethylene diamine, N,N-diethyl-1,3-propanediamine, diethylenetriamine, triethylene tetramine and imino bis(propylamine) in a liquidadduct of a poly (alkylene oxide) polyamine and a polyphenol.
 2. Thecomposition of claim 1 wherein the polyepoxide is one containing morethan one group of the formula ##STR2##
 3. The composition of claim 2wherein the poly(alkylene oxide) polyamine has a molecular weight offrom 200 to 10,000.
 4. The compoition of claim 3 wherein the weightratio of the polyamine polyphenol salt to the liquid adduct of thepoly(alkylene oxide) polyamine-polyphenol in the second component is inthe range of from 5:95 to 60:40.
 5. The composition of claim 4 whereinthe poly(alkylene oxide) polyamine in the second component is oneprepared by the amination of poly(alkylene oxide) polyols and isselected from the group consisting of poly(propylene oxide) diamines andpolypropylene oxide triamines.
 6. The composition of claim 5 wherein thesolid salt of the second component is the salt of ethylenediamine/Bispheonol-A and the liquid adduct is the adduct ofpoly(propylene oxide) triamine and Bisphenol-A.
 7. The composition ofclaim 5 wherein there is also included in the first component thediglycidyl ether of poly(propylene oxide) diol.